1. Field of the Invention
This invention relates to apparatus for coupling an optical fibre to a waveguide on an optical chip.
2. Description of the Prior Art
Many different arrangements have been proposed and used for coupling an optical fibre to a waveguide integrated on an optical chip to ensure that the fibre and waveguide are positioned in alignment with each other and to provide a low-loss coupling for the transmission of optical signals from the fibre to the waveguide and vice versa.
One known method of coupling a fibre to a waveguide is disclosed in WO97/42534. In this arrangement, a V-groove is provided in a silicon-on-insulator chip. Due to the manner in which the V-groove is etched, the end face of the groove is not perpendicular to the plane of the chip but is inclined thereto. Accordingly, in order to enable a close, abutting relationship between the end of the fibre and the end of the waveguide to be provided, the waveguide is constructed so as to overhang the inclined end face of the groove. This arrangement works well in many situations but in some applications there is concern that the overhanging portion of the waveguide may not be sufficiently robust to withstand harsh conditions to which it may be subjected.
The invention aims to provide an alternative arrangement which is likely to be more robust yet is still simple, easy to fabricate and facilitates passive alignment of the fibre with the waveguide.